The art of dentistry has been practiced for centuries. Initially, primitive instruments were used to manipulate a person's teeth for purposes of extraction and the like. Unfortunately, most of the procedures and operations performed by dentists were painful and there were few means for minimizing this pain. As the science of dentistry progressed, more was learned about oral care and associated implements and tools were developed to facilitate the operating dentist. One problem, however, still lingers for dentist and patient, and that is that a substantial degree of pain and discomfort remains associated with dental visits. Though significant strides have been made in these regards, and whether or not the discomfort associated with dental procedures is real or assumed by the patient, there is still a great deal of apprehension experienced by a person in anticipation of a visit to the dentist.
Together with other types of surgical procedures, the science of dentistry has been successful in alleviating extreme pain associated with dental procedures. Discomfort, however, is still a common experience of dental patients and an obstacle to dental care that dentists wish to diminish. A substantial hurdle that dentists have had to overcome is the fact that teeth are complex structures comprised of very hard outer surfaces that protect softer and extremely sensitive interiors. As a result, great force has been traditionally employed and applied to mechanical abrading instruments to penetrate and prepare the hard outer coating of the teeth. Consequently, extreme care must be used by the dentist to only abrade the outer surface without conflicting with the sensitive core of the tooth.
Most dental procedures are performed while the patient is conscious, but local anesthetics are administered to the effected area to mask the potentially extreme pain that could otherwise be experienced. Necessarily, several uncomfortable "evils" still plague people's perceptions of dental visits. The first is the expectation of at a minimum, receiving an uncomfortable shot in the mouth that produces a strange numb feeling that lingers after the procedure, slowly wearing off in due time after leaving the dentist's office. Secondly, several other disdainful experiences stem from the relatively high pressures applied upon the teeth. One such effect or result is frictionally produced heat associated with conventional mechanical drilling and abrading processes. In many instances, the dentist must apply heavy mechanical force in terms of rotary instrumentation in order to penetrate the hard outer surface. The penetration of enamel with rotary instrumentation is painful without anesthesia. Even with local anesthetic, the obnoxious vibration and sound associated with rotary drills is uncomfortable at best, and causes apprehension in the patient. Furthermore, the instruments that have been traditionally used in these procedures are high speed and slow speed rotary drills. A significant amount of friction is caused by the action of the instrument on the tooth resulting in heat and an associated burning or "hot" malodor. The heat must be dissipated prior to reaching uncomfortable levels and the smell is something the patient must endure. Patients also experience discomfort caused by vibration of the rotary instruments that manifest as bone-conducted noise that can be very irritating during treatment.
The drilling and abrading of a tooth normally serves a dual purpose. The first is to remove undesirable portions of the tooth such as hypocalcified enamel, decay or old filling material. The second is to prepare the revealed surface of the tooth for receiving a filler or coating material that will protect the affected area in the future. An often encountered problem is that the mechanical means for wearing portions of the tooth away are not exact and produce a variable surface corresponding to the shape of the rotary bur and which often creates sharp edges and recesses at their intersections. These effects of rotary instrumentation are undesirable for at least three reasons. The first is that the resulting apexes establish stress concentration points within the tooth structure thereby compromising its inherent solidarity. The second is that the vibration and heat from high speed rotary instrumentation creates crack and craze lines in the enamel and dentin of the tooth leading to more pathology. Thirdly, rotary instrumentation also creates a "smear" layer of indiscriminant ground particles on the surface which acts as a contaminant.
In response to the above outlined detrimental effects associated with conventional drilling and grinding dental instruments and techniques, alternatives have been developed. One such alternative is generally referred to as air-abrasion systems. These systems capitalize on characteristics that can best be understood as a highly focused "sandblasting" of the tooth. A forceful stream of particles can be directed upon a tooth to either affect its surface, or by more prolonged use to cut portions of the tooth away. This method can be utilized much like a mechanical drill or rotary abrading instrument. It is even possible for this tool to be used to erode interior portions of the tooth after access is provided through a penetrating porthole.
Implementation of such air-abrasion systems occurred in dentistry at least as early as the 1950's. These early systems, however, were cumbersome and often were inexact with respect to the particulate matter applied to the tooth. These are critical parameters because they determine the effectiveness of the treatment and the willingness of dentists to employ them. They also negatively affect accuracy of the procedures. There were also mechanical deficiencies within the design of the early systems that often prohibited the suspension of a proper and consistent amount of particulate in an air stream. Blockages could also form in the passages if plugs of particle mass were accidentally picked up in the system and transported through necked regions of the delivery system. Still further, the early systems were expensive and not well understood; therefore, conventional dentistry did not heartily embrace the concept and the process never enjoyed much success.